Re: [Intel-gfx] [PATCH] drm/i915: Add bigjoiner force enable option to debugfs

["Sharma, Swati2" <swati2.sharma@intel.com>]

Hi Ville,

On 25-Oct-23 6:29 PM, Ville Syrjälä wrote:
> On Wed, Oct 18, 2023 at 04:24:00PM +0300, Stanislav Lisovskiy wrote:
>> For validation purposes, it might be useful to be able to
>> force Bigjoiner mode, even if current dotclock/resolution
>> do not require that.
>> Lets add such to option to debugfs.
>>
>> v2: - Apparently intel_dp_need_bigjoiner can't be used, when
>>        debugfs entry is created so lets just check manually
>>        the DISPLAY_VER.
>>
>> v3: - Switch to intel_connector from drm_connector(Jani Nikula)
>>      - Remove redundant modeset lock(Jani Nikula)
>>      - Use kstrtobool_from_user for boolean value(Jani Nikula)
>>
>> v4: - Apply the changes to proper function(Jani Nikula)
>>
>> Signed-off-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>
>> ---
>>   .../drm/i915/display/intel_display_debugfs.c  | 66 +++++++++++++++++++
>>   .../drm/i915/display/intel_display_types.h    |  2 +
>>   drivers/gpu/drm/i915/display/intel_dp.c       |  6 +-
>>   3 files changed, 73 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/i915/display/intel_display_debugfs.c b/drivers/gpu/drm/i915/display/intel_display_debugfs.c
>> index fbe75d47a165..9b810c6f96ea 100644
>> --- a/drivers/gpu/drm/i915/display/intel_display_debugfs.c
>> +++ b/drivers/gpu/drm/i915/display/intel_display_debugfs.c
>> @@ -1398,6 +1398,30 @@ out:	drm_modeset_unlock(&dev->mode_config.connection_mutex);
>>   	return ret;
>>   }
>>   
>> +static int i915_bigjoiner_enable_show(struct seq_file *m, void *data)
>> +{
>> +	struct intel_connector *connector = to_intel_connector(m->private);
>> +	struct drm_crtc *crtc;
>> +	struct intel_encoder *encoder = intel_attached_encoder(connector);
>> +	struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
>> +	int ret = 0;
>> +
>> +	if (!encoder)
>> +		return -ENODEV;
>> +
>> +	crtc = connector->base.state->crtc;
>> +	if (connector->base.status != connector_status_connected || !crtc) {
>> +		ret = -ENODEV;
> 
> Why do we need this extra complication?
> 
>> +		goto out;
>> +	}
>> +
>> +	seq_printf(m, "Bigjoiner enable: %d\n", intel_dp->force_bigjoiner_enable);
>> +
>> +out:
>> +
>> +	return ret;
>> +}
>> +
>>   static ssize_t i915_dsc_output_format_write(struct file *file,
>>   					    const char __user *ubuf,
>>   					    size_t len, loff_t *offp)
>> @@ -1419,12 +1443,39 @@ static ssize_t i915_dsc_output_format_write(struct file *file,
>>   	return len;
>>   }
>>   
>> +static ssize_t i915_bigjoiner_enable_fops_write(struct file *file,
>> +						const char __user *ubuf,
>> +						size_t len, loff_t *offp)
>> +{
>> +	struct seq_file *m = file->private_data;
>> +	struct intel_connector *connector = m->private;
>> +	struct intel_encoder *encoder = intel_attached_encoder(connector);
>> +	struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
>> +	bool bigjoiner_en = 0;
>> +	int ret;
>> +
>> +	ret = kstrtobool_from_user(ubuf, len, &bigjoiner_en);
>> +	if (ret < 0)
>> +		return ret;
>> +
>> +	intel_dp->force_bigjoiner_enable = bigjoiner_en;
>> +	*offp += len;
>> +
>> +	return len;
>> +}
>> +
>>   static int i915_dsc_output_format_open(struct inode *inode,
>>   				       struct file *file)
>>   {
>>   	return single_open(file, i915_dsc_output_format_show, inode->i_private);
>>   }
>>   
>> +static int i915_bigjoiner_enable_open(struct inode *inode,
>> +				      struct file *file)
>> +{
>> +	return single_open(file, i915_bigjoiner_enable_show, inode->i_private);
>> +}
>> +
>>   static const struct file_operations i915_dsc_output_format_fops = {
>>   	.owner = THIS_MODULE,
>>   	.open = i915_dsc_output_format_open,
>> @@ -1434,6 +1485,15 @@ static const struct file_operations i915_dsc_output_format_fops = {
>>   	.write = i915_dsc_output_format_write
>>   };
>>   
>> +static const struct file_operations i915_bigjoiner_enable_fops = {
>> +	.owner = THIS_MODULE,
>> +	.open = i915_bigjoiner_enable_open,
>> +	.read = seq_read,
>> +	.llseek = seq_lseek,
>> +	.release = single_release,
>> +	.write = i915_bigjoiner_enable_fops_write
>> +};
>> +
>>   /*
>>    * Returns the Current CRTC's bpc.
>>    * Example usage: cat /sys/kernel/debug/dri/0/crtc-0/i915_current_bpc
>> @@ -1513,6 +1573,12 @@ void intel_connector_debugfs_add(struct intel_connector *intel_connector)
>>   				    connector, &i915_dsc_output_format_fops);
>>   	}
>>   
>> +	if (DISPLAY_VER(dev_priv) >= 11 &&
>> +	    intel_connector->base.connector_type == DRM_MODE_CONNECTOR_DisplayPort) {
> 
> eDP missing
> 
>> +		debugfs_create_file("i915_bigjoiner_force_enable", 0644, root,
>> +				    &intel_connector->base, &i915_bigjoiner_enable_fops);
>> +	}
>> +
>>   	if (connector->connector_type == DRM_MODE_CONNECTOR_DSI ||
>>   	    connector->connector_type == DRM_MODE_CONNECTOR_eDP ||
>>   	    connector->connector_type == DRM_MODE_CONNECTOR_DisplayPort ||
>> diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
>> index 8d8b2f8d37a9..e0de6eeaf59e 100644
>> --- a/drivers/gpu/drm/i915/display/intel_display_types.h
>> +++ b/drivers/gpu/drm/i915/display/intel_display_types.h
>> @@ -1753,6 +1753,8 @@ struct intel_dp {
>>   	bool is_mst;
>>   	int active_mst_links;
>>   
>> +	bool force_bigjoiner_enable;
>> +
>>   	/* connector directly attached - won't be use for modeset in mst world */
>>   	struct intel_connector *attached_connector;
>>   
>> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
>> index 4f6835a7578e..6a9148232a9c 100644
>> --- a/drivers/gpu/drm/i915/display/intel_dp.c
>> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
>> @@ -1153,7 +1153,11 @@ bool intel_dp_need_bigjoiner(struct intel_dp *intel_dp,
>>   	if (!intel_dp_can_bigjoiner(intel_dp))
>>   		return false;
>>   
>> -	return clock > i915->max_dotclk_freq || hdisplay > 5120;
>> +	if (intel_dp->force_bigjoiner_enable)
>> +		drm_dbg_kms(&i915->drm, "Forcing bigjoiner mode\n");
> 
> That's going to cause excessive dmesg spam.

Then how from dmesg we will get to know, big joiner was forced? 
Shouldn't we have atleast one debug print to know this?

> 
>> +
>> +	return clock > i915->max_dotclk_freq || hdisplay > 5120 ||
>> +	       intel_dp->force_bigjoiner_enable;
>>   }
>>   
>>   static enum drm_mode_status
>> -- 
>> 2.37.3
>